libdspl-2.0/dspl/blas/src/scasum.f

118 wiersze
2.5 KiB
Fortran

*> \brief \b SCASUM
*
* =========== DOCUMENTATION ===========
*
* Online html documentation available at
* http://www.netlib.org/lapack/explore-html/
*
* Definition:
* ===========
*
* REAL FUNCTION SCASUM(N,CX,INCX)
*
* .. Scalar Arguments ..
* INTEGER INCX,N
* ..
* .. Array Arguments ..
* COMPLEX CX(*)
* ..
*
*
*> \par Purpose:
* =============
*>
*> \verbatim
*>
*> SCASUM takes the sum of the (|Re(.)| + |Im(.)|)'s of a complex vector and
*> returns a single precision result.
*> \endverbatim
*
* Arguments:
* ==========
*
*> \param[in] N
*> \verbatim
*> N is INTEGER
*> number of elements in input vector(s)
*> \endverbatim
*>
*> \param[in,out] CX
*> \verbatim
*> CX is COMPLEX array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
*> \endverbatim
*>
*> \param[in] INCX
*> \verbatim
*> INCX is INTEGER
*> storage spacing between elements of SX
*> \endverbatim
*
* Authors:
* ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date November 2017
*
*> \ingroup single_blas_level1
*
*> \par Further Details:
* =====================
*>
*> \verbatim
*>
*> jack dongarra, linpack, 3/11/78.
*> modified 3/93 to return if incx .le. 0.
*> modified 12/3/93, array(1) declarations changed to array(*)
*> \endverbatim
*>
* =====================================================================
REAL FUNCTION SCASUM(N,CX,INCX)
*
* -- Reference BLAS level1 routine (version 3.8.0) --
* -- Reference BLAS is a software package provided by Univ. of Tennessee, --
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
* November 2017
*
* .. Scalar Arguments ..
INTEGER INCX,N
* ..
* .. Array Arguments ..
COMPLEX CX(*)
* ..
*
* =====================================================================
*
* .. Local Scalars ..
REAL STEMP
INTEGER I,NINCX
* ..
* .. Intrinsic Functions ..
INTRINSIC ABS,AIMAG,REAL
* ..
SCASUM = 0.0e0
STEMP = 0.0e0
IF (N.LE.0 .OR. INCX.LE.0) RETURN
IF (INCX.EQ.1) THEN
*
* code for increment equal to 1
*
DO I = 1,N
STEMP = STEMP + ABS(REAL(CX(I))) + ABS(AIMAG(CX(I)))
END DO
ELSE
*
* code for increment not equal to 1
*
NINCX = N*INCX
DO I = 1,NINCX,INCX
STEMP = STEMP + ABS(REAL(CX(I))) + ABS(AIMAG(CX(I)))
END DO
END IF
SCASUM = STEMP
RETURN
END